The present invention relates to a method and a device for separating a flow of crops, which contains at least two material parts, designated as useful material or waste material, into a useful material flow and a waste material flow, in which, respectively, the useful material or waste material is concentrated.
Each separating process is a compromise between three specifications running counter to one another. A high flow rate of the separating method is necessary, in order to use efficiently the utilized resources, such as machines and labor and to maintain the costs of the separation at a minimum. With increasing flow rate, however, the selectivity of the separation is reduced. A high selectivity of the separation means, on the other hand, that the portion of useful material, which is moved into the waste material flow, should be as small as possible. That means that the useful material contained in the flow of crops should be obtained as completely as possible. On the other hand, the smallest possible waste material should be contained also in the useful material flow. Minimal waste of useful material generally can be achieved only when it is accepted that waste material is moved into the useful material flow, which, in turn, detrimentally affects the further ability to process and the value of the useful material so obtained. A high purity of the useful material flow must be purchased generally with losses of useful material.
In order to coordinate these counter specifications, it has been proven advisable to perform separating methods in two steps, in which in a first separating step, a pre-cleaned flow is produced, in which the useful material is maintained as completely as possible, and likewise, the remaining portion of waste material is accepted. It is important that the flow rate of the pre-cleaned flow is substantially reduced in comparison to the original flow of crops, so that the second separating step, which is applied to the most complete separation of the waste material as possible, can be effectively performed.
A two-stage separation of grain and non-grain material is prevalent with harvest combines. As an example, reference is made to U.S. Pat. No. 4,934,985, which describes a combine, in which a first separating step, with the aid of a threshing cylinder and separator cylinders, separating the flow of crops into straw, which is discarded, and flow containing grain and chaff, that is, spelt and fine stalk fragments, which are cleaned subsequently in a second separating step.
The separation of the pre-cleaned flow takes place in the common manner via so-called separating cages, in the form of perforated sheets or sieves, which are associated with a rotor, respectively, and which lets pass the grain-chaff mixture forming the pre-cleaned flow, while the straw is conveyed further by the rotor and finally thrown out. These separating cages are formed as sheet cages, that is, sheets, in which holes are applied with a fixed size specified for desired crops, or as a wire cage, which are formed by bars arranged in defined distances and provided with bores and wires, which are guided through the bores. The geometry of the openings is unchanging with all of these separating cages. An adaptation to the requirements of different thrashed fruit is therefore possible not only by an exchange of the separating cages or by changing their opening geometry, in which, for example, additional bars or sheets are screwed in. Such an adaptation is very time-consuming and when multiple separating cages must be held ready with different hole dimensions, it can also be very expensive.
However, if adapted cages are used always on the thrashed fruit to be processed, generally, an optimal separating result is not achieved with the actual technology. The basis for this is the qualities of the crop materials themselves, which can differ greatly, in particular, depending on their moisture. When one accepts that the first separating step is well adapted to a two-stage separating device to a selected crop with a specific degree of moisture, so that it can be operated with a high flow rate of the crops and run a pre-cleaned flow with a minimal waste portion, then generally, the second separating stage is not efficiently dimensioned based on economical grounds as is necessary to processing this pre-cleaned flow. If the crops are drier, then this facilities the separation in the first stage, so that this could be driven, in principle, with a higher flower rate, without increasing the useable material portion in its waste material flow over a permitted amount. With increasing drying, the crops, however, are subject also to increased formation of small fragment pieces, which are moved into the pre-cleaned flow and increased its waste material portion. An increased flow rate of the first separating stage therefore leads to an over-proportional increase of the flow rate, which must be processed by the second separating stage. This can be easily overloaded, therefore, with the result that its purification action is insufficient or can be achieved only with acceptance of a high loss of useable material. Generally, one can determine that the common two-stage separating methods and devices only achieve an optimal efficiency for a predetermined degree of dryness of the crops, in which both stages are working at their upper capacities. If the drying is stronger, the first stage must be driven beneath its capacity, in order not to overload the second. With a higher degree of moisture, this is reversed.
A combine with devices for detecting grain loss, which are arranged on a waste material flow, is known from DE 21 06 930 C3. The detection results of these devices are used in order to regulate the speed of the combine automatically or to produce a command for regulating the speed for the driver of the combine.
An object of the present invention is to provide a method and device for at least a two-stage separating of a flow of crops into a useable material flow and a waste material flow, which also makes possible with changing qualities of the flow of crops an operation of both stages at their upper capacities, and therewith, makes possible an optimal efficiency.
The object is solved by the method and device of the present invention. By regulating the selectivity of the first separating stage, the flow rate of the pre-cleaned flow processed by the second separating stage can be affected. This means that when the flow of crops to be processed is drier than an actual adjustment of the selectivity of the first stage, then by increasing the selectivity, the flow rate of the second stage can be reduced and so an overloading can be avoided.
In order to recognize an overload, at least one quantity combined with the amount of useable material into the waste material flows must be detected. Preferably, this is differently separated for each of the two waste material flows. Thus, also, a simultaneous overloading of both stages can be recognized and by reducing the flow rate of the flow of crops supplied to the first stage, counteracted.
Preferably, the amount of useable material contained in a waste flow is directly detected by measuring the waste material flow after the separating step. For example, this can occur in an acoustic way by detection of impact noise of the waste material flow, which is different for grains and blades contained in the flow.
Another possibility is to detect the amount of useable material contained in the waste material flow by measuring the material flow rate of the separating step that provides the waste material flow, whereby, then, the amount of lost useable material, for example, can be deduced with the aid of an empirically determined table or function.
A further possibility is to separate still a remaining, residual material flow in a second separating step in addition to the second waste material flow and the useable material flow, whose material could not be safely separated into useable material and waste material, and to detect the material flow rate of this residual flow.
Preferably, the selectivity of the first separating step is regulated, such that an equal portion of useable material is implemented in both waste material flows.
An adaptation of the selectivity of the separation to the detected portion of useable material into the waste material flows can take place fully automatically, or it can be produce a command to a user of the machine, that the selectivity should be increased or lowered, whereby it rests with the user to provide a corresponding adjustment.
When the useable material portion in both waste material flows exceeds a threshold value, this is then an instruction that both separating stages are overloaded and that the flow rate of the flow of crops should be reduced. In the reverse, in order to make possible an effective operation, the flow rate of the crops should be increased when the portion of a useable material in both waste material flows falls below a threshold value. When the invention is used on a drivable crop machine, it is recommend to increase or reduce the flow rate of the flow of crops by adapting the speed of the crop machine.
A preferred possibility is to automatically control the speed of the crop machine with reference to the detected useable material portion, in order release the driver of the machine from this responsibility. In order to avoid an unexpected acceleration and braking of the machine, it is also possible, however, merely to produce an instruction to the driver of the harvesting machine that the speed can be increased or reduced.